Thoughts on Proficiency and AC

I've been nagged by a minor inconsistency in 5E. (Just one? for the purposes of this thread, yes, just one. Well, maybe two.)

When you calculate the DC of just about everything in 5E, you add 8 + ability mod + proficiency bonus, if proficient. But when you calculate Armor Class, you add armor value + (possibly limited) dexterity bonus + shield value. So what happens if you use proficiency bonus with armor:

Armor
Armor Type
Light
Padded
Leather
Studded Leather
Medium
Hide
Chainshirt
Scale Mail
Breastplate
Half Plate
Heavy
Ring Mail
Chain Mail
Splint
Plate
Bonus

+1
+1
+2

+2
+3
+4
+4
+5

+4
+6
+7
+8
Max Dex Bonus

no limit
no limit
no limit

+2
+2
+2
+2
+2

+0
+0
+0
+0
Min Str to use

-
-
-

-
-
-
-
-

-
13
15
15

So a first level paladin in Chain Mail would have a AC 16 (8 + 6 + 2 + 0). At 5th level it would become AC 17 (8 + 6 + 3 + 0). At 19th level AC 20 (8 + 6 + 6 + 0).

Shield proficiency does not add proficiency bonus.

Can Rogues and Bards become Expert with their Armor? Probably a bit OP. But imagine the 19th level rogue in Leather armor and 20 Dex having a 26 AC (8 + 1 + 12 + 5). In a serious game, I would not allow this. But in a fun game, why not?

Might need to give a few pluses to the existing higher level monsters to compensate. And I know the system is supposed to avoid that kind of chasing the mean. But I like the idea of characters getting better at using their armor to their advantage.
 

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dave2008

Legend
Might need to give a few pluses to the existing higher level monsters to compensate. And I know the system is supposed to avoid that kind of chasing the mean. But I like the idea of characters getting better at using their armor to their advantage.

Why not just add prof. bonus to monsters too? They generally use the same system as PCs now.
 

It makes sense to me. The only problem is that PCs are already ludicrously durable, and increasing their ACs at high levels would make them more-so. I would prefer to address that by reducing HP to compensate, but there are any number of approaches you could take.
 

jgsugden

Legend
You're just raising PC ACs with this system at levels 5 to 20. The impact will be minor at 5 to 8. From 9 to 12 you'll feel it a bit more, but it won't be overwhelming. 13 to 16 will be noticeable for sure. At 17th level it is a +4 bonus. That changes a lot of the assumptions of the game at these high levels...

However, as many games don't really extend far beyond 13th level, it is not really that big of a deal.

All that being said, it would not interest me. The game is built on the assumption of flatter ACs at higher levels, so I prefer to keep within that expectation.
 

dwelwell

Villager
I like the idea. It provides a place for skill and expertise in defense, a concept sorely lacking in 5e. It also means you can be skill without having a high DEX, which is nice.
 

cbwjm

Legend
I like this, it does add some additional calculations to the game but that shouldn't be too much of a problem once the AC is worked out and play begins. None of the scores below include +2 for a shield.

With a maximum dexterity bonus (+5 for light armour, +2 for medium armour), both the best light armour and medium armour come out with a final AC of 21 at level 17 and heavy armour an AC of 22.

A wizard with mage armour is going to have an easier time of it. If they have a dexterity of 14 their whole career they have an AC range of 15 to 19 with mage armour up instead of a flat score of 15.

If monks and barbarians are to be considered proficient with unarmoured defence, they can end up with scores quite high. Starting score for a monk would often be 16 (8 +2 Prof. +3 Dex. +3 Wis) which is pretty standard, but at level 17 if the dexterity and wisdom scores are maxed they end up with 24 (8 +6 +5 +5). I guess that keeps the monk comparable with the magical bonuses for armour that others might get. Barbarians might be slightly less as they will be focusing on strength rather than dexterity in most cases, though they can use a shield as well.

This also gives a regular person with no armour, no Dexterity bonus an ascending AC from 10 to 14 (assuming that, like unarmed strikes, everyone is proficient in defending themselves) which I like a better than just 10 + dexterity.
 

Bardbarian

First Post
Why not just remove proficiency bonus all together? Adding Proficiency to defense makes the numbers meaningless. at level 5 I get a +1 to hit and you get +1 defense then what's the point we hit on the same number as last level. Defense is not supposed to scale with level, 5th edition uses HP as the defensive scaling factor.
 

cbwjm

Legend
Probably because the party members aren't generally fighting each other? Those low level orcs will have the same +2 proficiency modifier when the party has a +3 modifier. Against opponents with the same proficiency bonus the bonuses do cancel out, but the whole world doesn't move along at the same pace as the PCs.
 

Why not just remove proficiency bonus all together? Adding Proficiency to defense makes the numbers meaningless. at level 5 I get a +1 to hit and you get +1 defense then what's the point we hit on the same number as last level.
That would only be true in the specific case that you are fighting an enemy that's roughly the same level as you are. If you're fighting a stronger or weaker enemy, then the difference would become much more apparent.
 

Damage per attack doesn't climb quite as fast as hps in 5e, the idea is you'll attack more often and hit /even more often/, so a climbing AC would presumably leave weapon attacks and attack cantrips trailing.

You'd want to reduce the armor bonuses by more than 2, if you're basing it on proficiency in armor.

You might, instead, bring proficiency in for more active defense, like dodging, or a limited AC for attacks you're aware of...

If you don't mind the complexity of 3e-style multiple ACs, you could even go with something like:

Armor would be passive AC, it's always there for you.

Proficiency + whatever would be when you're actively defending yourself in whatever sense, and could be 8+prof+stat for say, parrying with a weapon. 10 + prof + stat for a shield. When you're say, engaged with a target you can see, you get to use your armor AC, or your proficiency AC, whichever is higher. At range your weapon proficiency (probably) doesn't help (a high level feature for arrow-cutting maybe?), but 10+prof+stat for a shield wouldn't be crazy. If you use your action for defense the enemy has to hit both (kinda like disadvantage).

Since your Armor should usually give you better AC than your prof in this hypothetical system, it could be later-game complexity that you add in if people start /asking/ "hey, why am I not getting better at avoiding being hit?"

Of course, the old standby "that's reflected in your hps" is always there, too. ;)
 


I'm only complaining about the inconsistency. I'm not suggesting torches and pitchforks as we storm WotC demanding a change. I'm just asking what happens if you make every die roll DC based on the One True Formula: 8 + Prof + Ability Bonus? Obviously a change to the system requires propagated changes to other parts of the system.

Oh, and my OP did forget to mention Monks and Barbs would be considered proficient in Unarmored Combat. Thanks to whomever asked about that.
 

Riley37

First Post
Alternate plan: without proficiency, shield provides +1 AC. (Even passively, a shield gets in the way of some attacks.) If you have proficiency with shields, then instead, shield provides (proficiency bonus) to AC, representing your trained ability to move the shield into the way of attacks.

Armor proficiency doesn't make much sense to me. Does anyone with SCA or similar experience think that moving effectively while wearing armor, requires three cumulative levels of training?
 

Armor proficiency doesn't make much sense to me. Does anyone with SCA or similar experience think that moving effectively while wearing armor, requires three cumulative levels of training?
That's two different questions. Is there a difference between light, medium, and heavy armor versus can proficiency with armor help protect you from damage. Armor in D&D has always been handled "oddly" since one would assume armor reduces damage instead of preventing "hits". So my question is purely a game mechanics question. Not a simulation question.
 


77IM

Explorer!!!
Supporter
I like the concept, but as others have pointed out, 5e's math isn't really built to accommodate it. Monsters' to-hit bonuses are already too low, and this would make them even whiffier.
 

Tormyr

Adventurer
My understanding is that AC is the one DC that does not scale because HP is instead scaling upward (and is offset by DPR scaling up). The PCs are not supposed to be hit less often just because they are increasing in level. Rather, they should be hit as often or more often because the +to hit bonus for the enemy increases by as much or more than the AC increases that the PCs pick up. The HP increases counterbalance this and do go up every level.

Part of the way bounded accuracy has been set up in 5e is that almost any creature can hit almost any other creature without requiring a critical hit. This allows large numbers of low-CR creatures to be used in high-level encounters because some of them are still able to hit.

Allowing the PCs to have super-high AC at high levels makes encounters significantly easier and eliminates low-CR creatures from high-level encounters. In essence, the PCs get a free +1 AC ring at level 5, +2 at level 9, +3 at level 13, and +4 at level 17. This combines with any magical items and armor the PC has. Around level 13, a point-buy monk with no magic items could potentially have an AC of 22; a similar barbarian could have an AC of 24 with a shield. At that point, many low-CR creatures are useless, and even adult dragons are missing roughly half the time.

Personally, I would not suggest altering AC just because the numbers are calculated differently. HP is the defensive number that scales with level so that a creature can be hit more often but survive it (and burn healing resources).

My 2cp.
 

Tormyr

Adventurer
I'm only complaining about the inconsistency. I'm not suggesting torches and pitchforks as we storm WotC demanding a change. I'm just asking what happens if you make every die roll DC based on the One True Formula: 8 + Prof + Ability Bonus? Obviously a change to the system requires propagated changes to other parts of the system.

Oh, and my OP did forget to mention Monks and Barbs would be considered proficient in Unarmored Combat. Thanks to whomever asked about that.

It is not really "The One True Formula" however. Saving Throw DCs are calculated that way. Attack Roll DCs are based on however AC is calculated for a creature. Ability Check DCs are calculated based on contested rolls, assumptions on real world difficulty, desired challenge, or any number of other reasons including the DM's mood. There are 3 different kinds of d20 rolls in D&D, and the DC for each of them is calculated differently.
 

TheSword

Legend
My biggest issue with this is that it waters down the effect of higher AC from armour at higher levels. I already see too many dex based characters and this would just compound that problem. Effectively you adding +1 to every characters AC every 4 levels.

Totally agree with [MENTION=6776887]Tormyr[/MENTION] that hp are a better representation of taking more damage.
 

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